With the gradual popularization of network communications, network security becomes a big concern for people. Currently, in most of network operations conducted by users, an authentication in a certain form will be carried out between each other (i.e. a user and service provider of a network side) to guarantee the communication security of both parties. For example, a user, when access to a specific network or login a mailbox, usually need to enter his username and password and is allowed to access only if he is verified. Generally, a higher security is required when a user is making payments online, then certainly usernames and passwords are required to be input, and even additional measures in other forms such as proofs such as secret keys, certificate, or the like, are also required to guarantee security of communications.
Nevertheless, although various more and more complicated encrypted algorithms and data transmission methods are proposed to protect communication security, users' private information still easily got stolen. For instance, in the existing solutions, users always entered their private information (such as passwords, ect.) in some network connections which they believed reliable, but the private information is always stolen by a malicious third party. Thus, how to identify the reliability of communication sessions is still a concern for technicians.